Endemic skeletal fluorosis is the most important metabolic bone disorder found in India. Secondary hyperparathyroidism is thought to contribute to the skeletal changes found in this disease. This fellowship shall enable me to study mechanisms of hyperparathyroidism induced by fluoride using an in vitro cell culture model. In addition, the ability of vitamin D to prevent these changes shall also be tested. The overall significance of the work will be to provide a better understanding of the pathogenesis of bone disease in fluorosis and perhaps help in developing an effective form of therapy. It shall also enable me to learn the techniques of parathyroid cell culture, which can be useful for studying a variety of other disorders related to calcium metabolism.